Methods and apparatus for node caching at the file level

Abstract

Methods and apparatus for caching files in DOS based computer systems are disclosed wherein the computer systems include a nonstandard drive in which files have been stored and from which files can be accessed, retrieved or written to, a computer CPU for generating instructions for accessing, retrieving or writing portions of desired files, wherein said instructions for accessing, retrieving or writing are generated through the use of DOS interrupt 21 and a drive, recognized by the computer CPU as a DOS drive, for storage and access, retrieval or writing of files, wherein the access, retrieval or writing of files from the drive can be achieved faster than access, retrieval or writing of files from the non-standard drive. A file handler monitors CPU generated instructions directed through DOS interrupt 21 and in response to instructions for accessing, retrieving or writing portions of the files, the file handler retrieves information contained in files from the non-standard drive and caches the information in the drive. The disclosed computer system can also include a plurality of non-standard and standard drives to which the file handler is attached. In such an embodiment, the file handler is either preset as to which of the non-standard drives should be cached or not, or the file handler includes code for selecting or not the nonstandard drives to be cached. Such selective caching can be extended to particular files as well. In addition, methods of nonstandard drive selection can be extended to include a plurality of standard drives.

What is claimed: 
     
       1. A DOS based computer system having node caching at a file level, said system comprising: a CPU for generating instructions, wherein said instructions include those for accessing, retrieving or writing to portions of files or entire files, wherein the instructions for accessing, retrieving or writing contain those instructions directed through DOS interrupt 21;   a non-standard DOS drive in which desired files or nodes have been stored and from which said desired files or nodes can be accessed, retrieved or written, said desired files or nodes containing stored information;   a standard DOS drive, recognized by said CPU as a standard DOS drive, adapted for storage of file information and access, retrieval or writing of files, wherein the access, retrieval or writing of files from said standard DOS drive can be achieved faster than access, retrieval or writing of files from said non-standard DOE drive; and   a file handler, connected to said non-standard DOS drive, said standard DOS drive, and to said CPU, wherein said file handler monitors said CPU generated instructions directed through DOS interrupt 21 and caches portions of said desired files or nodes from said non-standard DOS drive in said standard DOS drive in response to instructions directed through DOS interrupt 21 for accessing, retrieving or writing said portions of said desired files or nodes from said non-standard DOS drive.   
     
     
       2. The system of claim 1, wherein said file handler monitors said CPU generated instructions directed through DOS interrupt 21 and retrieves the entire file including said portions from said non-standard DOS drive in response to instructions directed through DOS interrupt 21 for accessing, retrieving or writing said portions of said desired files from said non-standard DOS drive. 
     
     
       3. The system of claim 2, wherein retrieval by said file handler comprises copying the entire file to said standard DOS drive. 
     
     
       4. The system of claim 2, wherein retrieval by said file handler comprises moving the entire file to said standard DOS drive. 
     
     
       5. The system of claim 1, further comprising a plurality of non-standard DOS drives to which said file handler is attached. 
     
     
       6. The system of claim 5, wherein said file handler is preset as to which of said non-standard DOS drives is to be cached. 
     
     
       7. The system of claim 5, wherein said file handler comprises code for selecting which of said non-standard DOS drives is to be cached. 
     
     
       8. The system of claim 5, wherein said file handler is preset as to which of said non-standard DOS drives are not to be cached. 
     
     
       9. The system of claim 5, wherein said file handler comprises Code for selecting which of said non-standard DOS drives are not to be cached. 
     
     
       10. The system of claim 1, wherein said file handler is preset as to which files are to be cached in the standard DOS drive by said file handler. 
     
     
       11. The system of claim 1, wherein said file handler comprises code for selecting which files are to be cached in the standard DOS drive by said file handler. 
     
     
       12. The system of claim 1, wherein said file handler is preset as to which files are not to be cached in the standard DOS drive by said file handler. 
     
     
       13. The system of claim 1, wherein said file handler comprises code for selecting which files are not to be cached in the standard DOS drive by said file handler. 
     
     
       14. The system of claim 1, wherein said file handler monitors said CPU generated instructions directed through DOS interrupt 21 and retrieves a part of a desired file from said nonstandard DOS drive in response to instructions directed through DOS interrupt 21 for accessing, retrieving or writing said desired files from said non-standard DOS drive, said part including information requested by said CPU from said desired file. 
     
     
       15. The system of claim 1, further comprising a plurality of standard DOS drives to which said file handler is attached, each of said standard DOS drives recognized by said CPU as a DOS drive, each of said standard DOS drives targeted for storage of file information from said non-standard DOS drive for access, retrieval or writing of files, wherein the access, retrieval or writing of files from each standard DOS drive can be achieved faster than access, retrieval or writing of files from said non-standard DOS drive. 
     
     
       16. The system of claim 15, wherein said file handler is preset as to which one of said plurality of standard DOS drives is to be used to cache information from the non-standard DOS drive. 
     
     
       17. The system of claim 15, wherein said file handler comprises code for selecting which one of said plurality of standard DOS drives is to be used to cache information from the non-standard DOS drive. 
     
     
       18. The system of claim 15, wherein said file handler is preset as to which non-standard drive information is to be cached in one of the plurality of standard DOS drives by said file handler. 
     
     
       19. The system of claim 15, wherein said file handler comprises code for selecting which non-standard drive information is to be cached in one of the plurality of standard DOS drives by said file handler.